The field of art to which the claimed invention pertains is hydrocarbon separations. More specifically, the claimed invention relates to the separation of a C.sub.10 aromatic isomer from a hydrocarbon feedstream containing a mixture of C.sub.10 aromatic isomers by use of the adsorbent zeolite beta which selectively removes a C.sub.10 aromatic isomer from the feedstream. The selectively adsorbed C.sub.10 aromatic isomer is removed from the adsorbent through a desorption step. In one embodiment, durene is selectively removed from a mixture of C.sub.10 aromatic isomers containing the tetramethylbenzene isomers. In another embodiment, paradiethylbenzene is removed from a mixture of C.sub.10 aromatic isomers containing the diethylbenzene isomers. In general, paradiethylbenzene is preferentially adsorbed over the other C.sub.10 aromatic isomers. In one embodiment, paradiethylbenzene is preferentially adsorbed over the other C.sub.10 aromatic isomers with an order for decreased preference of adsorption on zeolite beta as follows: paradiethylbenzene&gt;durene&gt;metadiethylbenzene&gt;orthodiethylbenzene and prehnitene&gt;isodurene.